Roots-type and screw-type positive displacement compressors are employed in industrial and automotive applications. The compressor or supercharger may be operatively connected to an internal combustion engine to increase the amount or volume of intake air communicated to the internal combustion engine thereby increasing the volumetric efficiency of the internal combustion engine. The supercharger typically includes two interleaved counter-rotating rotors, each of which may be formed with a plurality of lobes operable to convey volumes of intake air from an inlet passage to an outlet passage for subsequent introduction to the internal combustion engine. The efficiency of the supercharger is dependent on the running clearances between the two rotors and between each of the two rotors and a housing within which the two rotors are rotatably supported.